From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 55A75C433EF for ; Thu, 16 Jun 2022 04:53:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S242923AbiFPExI (ORCPT ); Thu, 16 Jun 2022 00:53:08 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54000 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229681AbiFPExH (ORCPT ); Thu, 16 Jun 2022 00:53:07 -0400 Received: from pb-smtp21.pobox.com (pb-smtp21.pobox.com [173.228.157.53]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B476422283 for ; Wed, 15 Jun 2022 21:53:06 -0700 (PDT) Received: from pb-smtp21.pobox.com (unknown [127.0.0.1]) by pb-smtp21.pobox.com (Postfix) with ESMTP id 5332C18A64E; Thu, 16 Jun 2022 00:53:06 -0400 (EDT) (envelope-from junio@pobox.com) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed; d=pobox.com; h=from:to:cc :subject:references:date:in-reply-to:message-id:mime-version :content-type; s=sasl; bh=nHx6IK8ZAjd+a0iXRF8KUwp3+uRbPB4PuxJxLD UuJwY=; b=W+cyIv48qpMOz7tB0WrwKBn4TOMUWeIbrKf+dyvQemXDDCzEynk79r GxQxMnVkc2dnXraGxgph2YuEFdTwvmCdZ/pguhR+aHcWZqdmyWL4w9h/5D6+N+w8 rChtrwTHKiaOfSUeFnHyMIoy0vGqxr15STMhfgUQ2CcvjIqIiaTrg= Received: from pb-smtp21.sea.icgroup.com (unknown [127.0.0.1]) by pb-smtp21.pobox.com (Postfix) with ESMTP id 4C2EB18A64C; Thu, 16 Jun 2022 00:53:06 -0400 (EDT) (envelope-from junio@pobox.com) Received: from pobox.com (unknown [34.82.80.254]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by pb-smtp21.pobox.com (Postfix) with ESMTPSA id E88FC18A64B; Thu, 16 Jun 2022 00:53:02 -0400 (EDT) (envelope-from junio@pobox.com) From: Junio C Hamano To: "Johannes Schindelin via GitGitGadget" Cc: git@vger.kernel.org, Johannes Schindelin Subject: Re: [PATCH 06/11] pack-redundant: avoid using uninitialized memory References: Date: Wed, 15 Jun 2022 21:53:01 -0700 In-Reply-To: (Johannes Schindelin via GitGitGadget's message of "Wed, 15 Jun 2022 23:35:40 +0000") Message-ID: User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.2 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain X-Pobox-Relay-ID: 341517F2-ED30-11EC-8FF7-CBA7845BAAA9-77302942!pb-smtp21.pobox.com Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org "Johannes Schindelin via GitGitGadget" writes: > From: Johannes Schindelin > > In the `add_pack()` function, we forgot to initialize the field `next`, > which could potentially lead to readin uninitialized memory later. > > Reported by Coverity. > > Signed-off-by: Johannes Schindelin > --- > builtin/pack-redundant.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/builtin/pack-redundant.c b/builtin/pack-redundant.c > index ed9b9013a5f..1f7da1f68b6 100644 > --- a/builtin/pack-redundant.c > +++ b/builtin/pack-redundant.c > @@ -526,6 +526,7 @@ static struct pack_list * add_pack(struct packed_git *p) > } > l.all_objects_size = l.remaining_objects->size; > l.unique_objects = NULL; > + l.next = NULL; > if (p->pack_local) > return pack_list_insert(&local_packs, &l); > else return pack_list_insert(&altodb_packs, &l); The pack_list_insert reads like so: static inline struct pack_list * pack_list_insert(struct pack_list **pl, struct pack_list *entry) { struct pack_list *p = xmalloc(sizeof(struct pack_list)); memcpy(p, entry, sizeof(struct pack_list)); p->next = *pl; *pl = p; return p; } IOW, we prepare members of "l", pass it as "entry" to pack_list_insert(), but the helper function allocates a new piece of memory, copies "l" to it, and then sets the .next member of it to a reasonable value. And after that, the "l" that was merely used as a template goes out of scope. So I think this is a false positive. memcpy(p) does copy the uninitialized garbage that is held in entry->next to p->next, but it is overwritten with a reasonable address immediately after that.